Various types of medical devices employ a needle for piercing the skin of a patient for diagnostic or therapeutic purposes. One such device is a vial injector. Vial injectors utilize pre-filled vials that have a pre-measured dose of medication. The vial injector is used to inject the medication from the vial into a patient.
Handling of such needle-bearing medical devices after the needle is withdrawn from the patient can result in transmission of various pathogens, most notably human immune virus (HIV), to uninfected medical personnel, due to an inadvertent needle stick. Accordingly, it is desirable to provide a device for injecting medication from a pre-filled vial, wherein the injection needle is retracted into the housing of the device after use.
There are numerous retractable needle medical devices disclosed in the prior art. Typically, to effectuate retraction, the prior art devices require manual actuation by the operator. In many situations, such as an emergency situation, the operator is distracted or rushed so that the manual step necessary to effectuate retraction is not performed, either intentionally or unintentionally. In such instances, the used needle remains exposed, creating a risk of an inadvertent needle stick. Therefore, it would be desirable to provide an automatic needle retraction mechanism in which needle retraction is effectuated by normal operation of the device without the need to perform a separate manual step. It is further desirable to provide a device with a limited number of components so that the device can be produced cost effectively.